FIRST PHASE OF LUNAR EXPLORATION COMPLETED:

Landing Sites for the Last Missions

In July 1969 the Apollo Site Selection Board had compiled a list of 10
landing sites for Apollo 11-20, subject to further evaluation and
revision in light of the results of early landings [see Chapter 10][see
Table 2]. In August and September, responding to a request from
Headquarters and MSC program managers for detailed science mission
plans, members of the Group for Lunar Exploration Planning and its Site
Selection Subgroup, working with MSC operations planners and U.S.
Geological Survey scientists, suggested some minor changes, based on a
reevaluation of geologic features at one of the sites and the expected
availability of good photography at another. These were endorsed by the
Group for Lunar Exploration Planning on August 23.52

At the end of September, however, while many other complaints were being
registered concerning Apollo [see Chapter
10], some members of the Science and Technology Advisory Panel
and the lunar panel of the Lunar and Planetary Missions Board objected
that their opinions were not receiving sufficient consideration in site
selection. Harold Urey complained that he did not know who was making
decisions regarding landing sites, nor what the reasons for choosing the
various sites were: the correspondence he received was unintelligible,
full of unexplained acronyms and couched in unreadable bureaucratic
jargon. He could not take the time to attend meetings of the site
selection subgroup to argue his case, however, because of academic
commitments.53 Another meeting was held
in mid- October in the hope of considering the advice of the objectors,
but they were unable to attend. Gene Simmons, MSC's chief scientist, was
annoyed and disappointed. He wrote to the chairman of the Science and
Technology Advisory Committee,

To those of us who have been intimately involved with
the scientific recommendations on Apollo sites for some time, it was
particularly disappointing that only one of these "senior
scientists" showed up in time for the meeting. . . . The entire
decision-making process of NASA on the landing sites for the H and J
series missions was postponed in order for these individuals to meet
with us and provide the kind of counsel that only they, presumably,
could give. . . . [Nonetheless,] we as a group felt that we should
proceed with the reexamination of the proposed landing sites.54

The meeting went on without the objecting members, thoroughly reviewing
the sites and the scientific rationale and operational restrictions for
each. After two days of intensive review, the group endorsed the
proposed list of sites without alteration [see
Table 3]. 55

The Site Selection Board, meeting at the end of October, discussed this
list in light of the improvements (lunar roving vehicle and added
payload) expected for the J missions. Marius Hills, Descartes, and
Hadley appeared to present no problems of accessibility, but Copernicus
and Tycho were only marginally acceptable. Marius Hills was accessible
only during two summer months. Descartes, Hadley-Apennine, Davy Rille,
and Censorinus were not adequately covered by available site
photographs. MSC was prepared to accept the' available photographic
coverage for Fra Mauro, Littrow, Marius Hills, Copernicus, and Hyginus,
but planners would have to sacrifice some fidelity in terrain models for
training. Tycho was discussed at some length. It was the most difficult
site on the list to reach, but in many ways was scientifically
attractive. Finally the board relegated Tycho to the last J mission,
which would leave ample time to look for ways to overcome the
operational limitations. Houston's representative proposed yet another
sequence of missions [Table 4], which the
board approved as a basis for continuing evaluation.56

Assignment of sites to specific missions was tentative at this stage of
the project because the necessary information was still sketchy. By the
end of 1969, however, much of this information was becoming available.
Apollo 12 demonstrated the ability to make precision landings, a
requirement for the later H missions. As the initial scientific study of
samples from Apollo 11 and 12 yielded information on chemical
composition and age, the basis for choice among the remaining sites
became somewhat more clear-cut. On the other hand, in January 1970
Apollo 20 was canceled, and the prospect that others might be dropped
clouded the picture.

In February 1970 the Group for Lunar Exploration Planning met at Houston
to reassess the fist of sites in fight of recent developments and to
make new recommendations to the Site Selection Board. Tycho was
reluctantly dropped from consideration because of its operational
problems, although the group indicated that location was still
interesting. The remaining sites on the list approved in October were
endorsed, with minor changes. Fra Mauro remained the highest priority on
the list because it offered the chance to sample material that
originated deep within the moon. The group wanted to move Marius Hills
from the second to the first J mission, interchanging it with Descartes.
It specified that the target on the fourth "H" mission should
be as near the highland terrain around Davy Rille as possible, to be
reasonably sure of sampling highland material; otherwise Censorinus was
preferred. Finally, the group recommended that the site for the landing
at Hadley (J-4) be moved from the west side of Hadley Rille to the east
side, to allow the astronauts to reach the Apennine Front and sample
more than one type of terrain.57

MSC's Science and Applications Directorate evaluated this list with
three guiding principles in mind: information gained from previous
missions should weigh heavily in selection of later sites; since only a
few missions remained, sites should be chosen to answer as many
scientific questions as possible and missions should have multiple
objectives; and the sites of undisputed scientific interest should be
scheduled as early as possible. On this basis, MSC recommended shifting
Copernicus to Apollo 16 and the Marius Hills to Apollo 18. The
objectives at the Marius Hills site might be satisfied at either Davy or
Copernicus, and some of the instrumentation desired for a Marius Hills
mission might not be developed in time to fly on Apollo 16. Should that
be the case, a delay would imperil the sequence, because the useful
payload for a Marius Hills mission fell off by as much as 6,000 pounds
(2,720 kilograms) after midyear.*58

After the Apollo 13 mission had to be aborted, the Group for Lunar
Exploration Planning reconsidered its recommendations and endorsed Fra
Mauro (the planned Apollo 13 site) for Apollo 14. Its importance in
dating the Imbrian event remained, and it offered advantages for
placement of another passive seismometer, an active seismometer, and a
third laser retroreflector. For Apollo 15, the Group recommended a site
near the Davy crater chain, assuming adequate photography could be
obtained on 14.59

As it turned out, the photos from Apollo 14 would come too late to allow
certification of Davy as a site for Apollo 15, and in June the site
selection subgroup convened once more to evaluate candidate sites for
Apollo 15 and 16. By that time it was already clear that more missions
might be canceled, which further complicated the subgroup's
deliberations. After a long discussion that reexamined 14 sites** for which reasonably adequate photographs
were available, the subgroup agreed on a recommendation that the Marius
Hills be the candidate for Apollo 15. Littrow was the chosen alternate.
For Apollo 16, Descartes was the landing site of choice. In the event
that Apollo 15 was canceled, Marius Hills should be shifted to Apollo 16
and Descartes to 17. The remaining sites were ruled out, either because
MSC had determined that they were unsuitable for landing or because they
appeared to offer insufficient new scientific information to justify
consideration.60 Following this meeting
only Littrow, Descartes, Hadley- Apennines, and the Marius Hills
remained as strong candidates for the last missions.

In the next three months, MSC began to try to overcome the difficulties
in getting a consensus on landing sites among the various scientific
groups.*** Anthony Calio decided to
ask three groups of scientists to examine the question separately and
make independent recommendations. After receiving their opinions, Calio
summarized the criteria for selection of an Apollo 15 site. It should
offer a major advance in the study of the moon and a high probability of
answering essential scientific questions and satisfying the objectives
of more than one scientific discipline; it should be certifiable on the
basis of existing photography and not dependent on photographs to be
obtained by Apollo 14; it should be operationally feasible without
further analysis; and it should be appropriate for either a walking
mission or a rover mission, so that it could be flown on Apollo 15 or
(if 15 should be canceled) 16. Calio then described the geologic
features of the Hadley-Apennine site, located on the eastern rim of
Palus Putredinus, nearly 30 degrees north of the moon's equator. Among
the sites still under consideration, Hadley was unique in offering
direct access, with or without a roving vehicle, to a mountainous
highland, a mare surface, and a sinuous rille. Furthermore, it appeared
on most of the priority lists produced by the disciplinary groups. It
would offer the advantage of establishing the high-latitude arm of a
well dispersed array of geophysical instruments, essential to
investigating the moon's interior (by seismology) and its orbital
librations (by measurements from the laser retroreflectors).61

After the cancellation of Apollo 15 and 19 in early September 1970, MSC
presented the case for Hadley at the Apollo Site Selection Board's
meeting later that month. Arguments for Hadley and Marius Hills were
fairly evenly matched, both from scientific and operational standpoints,
and the debate between the two was virtually deadlocked until astronaut
David Scott, recently picked to command Apollo 15 (see below), said that
he preferred Hadley although he thought he could land at either site.
Scott's opinion tipped the balance. The Board recommended Hadley for a
launch date between July and September 1971, Descartes for Apollo 16
between January and March 1972. The choice of a site for Apollo 17 was
left open; Marius Hills and Copernicus were the leading candidates, but
others (e.g., Littrow) were still in the running, and a new site might
be found in future orbital photography.62

The September meeting wrapped up the Apollo Site Selection Board's
unfinished business for the time being. After Apollo 14, scheduled for
the following April, it would reconvene to examine the list of sites in
light of the results of that mission.

* This was the result of the mission
rule requiring daylight launches and of the annual variation in the
geometric relationships of the earth, sun, and moon.

*** According to an MSC participant,
consensus among the scientists at a site selection meeting was nearly
impossible to obtain. Each individual repeatedly voted for the site of
his choice, and in the end, NASA (i.e., MSC) had to made the decision.
Brooks, Grimwood, and Swenson,Chariots for Apollo, p.365.

52. Scherer, "Minutes of the Apollo
Site Selection Board Meeting, Oct. 30, 1969"; Farouk El-Baz and D.
B. James, "Minutes of the August 12-14 Meeting of an Ad Hoc Working
Group on the Science Objectives of Apollo Missions 12-20," Bellcomm
Memo for File, Aug. 18, 1969.

53. Gene Simmons to Dr. Charles H.
Townes and Dr. John Findlay, Oct. 21, 1969; Urey to Townes and Findlay,
Oct. 27, 1969. Urey felt unable to attend more meetings because "I
shall miss three classes this quarter in my thermodynamics course - one
to attend the Flagstaff [site evaluation] meeting and two to collect
medal awards. . . . I cannot serve on more committees and do my
university work."